Galileo is Europe’s own global navigation satellite system, providing a highly accurate, guaranteed global positioning service under civilian control. It is inter-operable with GPS and GLONASS, the two other global satellite navigation systems.

By offering dual frequencies as standard, Galileo will deliver real-time positioning accuracy down to the metre range. It will guarantee availability of the service under all but the most extreme circumstances and will inform users within seconds of any satellite failure, making it suitable for safety-critical applications such as guiding cars, running trains and landing aircraft.

Galileo Architecture

The fully deployed Galileo system consists of 30 satellites (27 operational + 3 active spares), positioned in three circular Medium Earth Orbit (MEO) planes at 23 222 km altitude above the Earth, and at an inclination of the orbital planes of 56 degrees to the equator

The Galileo ground infrastructure will be composed of:

30-40 sensor stations;

3 control centres;

9 Mission Uplink stations;

5 telemetry, tracking and command (TT&C) stations

Operational Satellites

The first two operational Galileo satellites were launched from Europe's Spaceport in French Guiana in October 2011. Once the In-Orbit Validation (IOV) phase has been completed, the remaining satellites will be placed in orbit at regular intervals to reach Full Operational Capability (FOC).

The complete Galileo constellation will comprise satellites spread evenly around three orbital planes inclined at an angle of 56 degrees to the equator. Each satellite will take about 14 hours to orbit the Earth. One satellite in each plane will be a spare, on stand-by should any operational satellite fail.

The GIOVEs were aimed at testing Galileo positioning system technologies in orbit.

GIOVE-A

GIOVE-A, was launched in December 2005, its primary goal being to claim the frequencies allocated to Galileo by the International Telecommunications Union (ITU). It has also been used to test the design of two on-board rubidium atomic clocks.

GIOVE-A was the first European satellite to be launched into medium Earth orbit (MEO). It carries two environmental monitors that have been in operation almost continuously since launch, gathering vital data about the Galileo intermediate circular orbit environment and helping in the design of the full constellation.

GIOVE-B

Launched in April 2008, GIOVE-B was the first satellite to actually transmit Galileo signals. After launch, early orbit operations and platform commissioning, GIOVE-B's navigation payload was switched on and signal transmission commenced.

Key facilities in the testing of GIOVE-B signals include the GIOVE-B Control Centre at Telespazio's facilities in Fucino, Italy, the Galileo Processing Centre at ESA's European Space Research and Technology Centre (ESTEC) in the Netherlands, the ESA ground station at Redu, Belgium, and the Rutherford Appleton Laboratory (RAL) Chilbolton Observatory in the United Kingdom.

GIOVE-A2

GIOVE-A2 essentially extended the mission of its predecessor, GIOVE-A, securing the Galileo programme by maintaining the critical ITU frequency and facilitating the ongoing development of ground equipment.

Galileo satellite testbeds: GIOVE

In 2004 the Galileo System Test Bed Version 1 (GSTB-V1) project validated the on-ground algorithms for Orbit Determination and Time Synchronisation (OD&TS). This project, led by ESA and European Satellite Navigation Industries, has provided industry with fundamental knowledge to develop the mission segment of the Galileo positioning system.

GIOVE-A is the first GIOVE (Galileo In-Orbit Validation Element) test satellite. It was built by Surrey Satellite Technology Ltd (SSTL), and successfully launched on 28 December 2005 by the European Space Agency and the Galileo Joint. Operation of GIOVE-A ensured that Galileo meets the frequency-filing allocation and reservation requirements for the International Telecommunication Union (ITU), a process that was required to be complete by June 2006.

GIOVE-B, built by Astrium and Thales Alenia Space, has a more advanced payload than GIOVE-A. It was successfully launched on 27 April 2008 aboard a Soyuz-FG/Fregat rocket provided by Starsem.

A third satellite, GIOVE-A2, was originally planned to be built by SSTL for launch in the second half of 2008, but the construction was terminated due to the successful launch and in-orbit operation of GIOVE-B.

In-Orbit Validation (IOV) satellites

These testbed satellites were followed by four IOV Galileo satellites that are much closer to the final Galileo satellite design. The Search & Rescue feature is not installed. The first two satellites were launched on 21 October 2011 from Guiana Space Centre using a Soyuz launcher, the other two on 12 October 2012. These 4 IOV Galileo satellites were constructed by Astrium GmbH and Thales Alenia Space. On 12 March 2013, a first fix is performed using those four IOV satellites. Once this In-Orbit Validation (IOV) phase has been completed, the remaining satellites will be installed to reach the Full Operational Capability.

Full Operational Capability (FOC) satellites

Once this In-Orbit Validation (IOV) phase has been completed, the remaining satellites will be installed to reach the Full Operational Capability. And there will be 22 FOC satellites in total.

GNSS.asia is funded by the European Union within Horizon 2020, the EU Framework Programme for Research and Innovation, under grant agreement no 641615.